Proximity-based system and method for reducing gain imbalance in a bayer pattern and digital camera employing the same

1. A proximity-based system for reducing Gr-Gb gain imbalance, comprising: a sensor configured to provide an input Bayer pattern array containing amplitudes corresponding to Gr and Gb cells; and a processor coupled to said sensor and configured to compute for at least some of said Gr and Gb cells: closeness measures for pluralities of adjacent, same-type cells, weights for pluralities of adjacent, opposite-type cells based on said closeness measures wherein a monotonically decreasing function determines said weights, and weighted averages of said pluralities of said adjacent, opposite-type cells based on said weights and use said weighted averages to form an output Bayer pattern in which said Gr-Gb gain imbalance is reduced.

2. The system as recited in claim 1 wherein said pluralities of adjacent, same-type cells consist of four adjacent, same-type cells and said pluralities of adjacent, opposite-type cells consist of four adjacent, opposite-type cells.

3. The system as recited in claim 1 wherein said monotonically decreasing function is a step function.

4. The system as recited in claim 3 wherein said monotonically decreasing function, f 1 (x), is: f 1 ⁡ ( x ) = { 1 x < t 1 3 / 4 t 1 ≤ x < t 2 1 / 2 t 2 ≤ x < t 3 1 / 4 t 3 ≤ x < t 4 0 t 4 ≤ x wherein t 1 , t 2 , t 3 , and t 4 are thresholds.

5. The system as recited in claim 1 wherein said monotonically decreasing function, f 2 (x), is: f 2 ⁡ ( x ) = { g ⁡ (  x  / t )  x  < t / 2 1 - g ⁡ ( 1 -  x  / t ) t / 2 ≤  x  ⁢ ⁢ and ⁢ ⁢  x  < t 0 t ≤  x  wherein g( ) is an amplitude and t is threshold.

6. The system as recited in claim 1 wherein said processor employs said output Bayer pattern to perform a color filter array interpolation.

7. A proximity-based method of reducing Gr-Gb gain imbalance, comprising: providing an input Bayer pattern array containing amplitudes corresponding to Gr and Gb cells; computing for at least some of said Gr and Gb cells: closeness measures for pluralities of adjacent, same-type cells, weights for pluralities of adjacent, opposite-type cells based on said closeness measures wherein a monotonically decreasing function determines said weights, and weighted averages of said pluralities of said adjacent, opposite-type cells based on said weights; and using said weighted averages to form an output Bayer pattern in which said Gr-Gb gain imbalance is reduced.

8. The method as recited in claim 7 wherein said pluralities of adjacent, same-type cells consist of four adjacent, same-type cells and said pluralities of adjacent, opposite-type cells consist of four adjacent, opposite-type cells.

9. The method as recited in claim 7 wherein said monotonically decreasing function is a step function.

10. The method as recited in claim 9 wherein said monotonically decreasing function, f 1 (x), is: f 1 ⁡ ( x ) = { 1 x < t 1 3 / 4 t 1 ≤ x < t 2 1 / 2 t 2 ≤ x < t 3 1 / 4 t 3 ≤ x < t 4 0 t 4 ≤ x wherein t 1 , t 2 , t 3 , and t 4 are thresholds.

11. The method as recited in claim 7 wherein said monotonically decreasing function, f 2 (x), is: f 2 ⁡ ( x ) = { g ⁡ (  x  / t )  x  < t / 2 1 - g ⁡ ( 1 -  x  / t ) t / 2 ≤  x  ⁢ ⁢ and ⁢ ⁢  x  < t 0 t ≤  x  wherein g( ) is an amplitude and t is threshold.

12. The method as recited in claim 7 further comprising employing said output Bayer pattern to perform a color filter array interpolation.

13. A digital camera capable of carrying out front-end image processing and comprising: a sensor configured to provide an input Bayer pattern array containing amplitudes corresponding to Gr and Gb cells; and a processor coupled to said sensor and configured to compute for at least some of said Gr and Gb cells: closeness measures for four adjacent, same-type cells, weights for four adjacent, opposite-type cells based on said closeness measures wherein a monotonically decreasing function determines said weights, and weighted averages of said four adjacent, opposite-type cells based on said weights and use said weighted averages to form an output Bayer pattern in which said Gr-Gb gain imbalance is reduced.

14. The digital camera as recited in claim 13 wherein said monotonically decreasing function is a step function.

15. The digital camera as recited in claim 13 wherein said processor employs said output Bayer pattern to perform a color filter array interpolation.

16. A method of Bayer pattern Gr-Gb imbalance reduction, comprising the steps of: (a) providing an input Bayer pattern array of cell amplitudes with first, second, third, . . . , Nth green cells where N is a positive integer; (b) for said first green cell of said input Bayer pattern array, computing a closeness measure for each of the four adjacent green cells of the same Gr-Gb type as said first green cell; (c) for said first green cell using said closeness measures, computing weights for each of four adjacent green cells of the opposite Gr-Gb type as said first green cell; (d) for said first green cell using said weights, computing a weighted average with said four adjacent green cells of the opposite Gr-Gb type as said first green cell; (e) for each of said second, third, . . . , Nth green cells, repeating said steps of computing a closeness measure, computing weights, and computing a weighted average; and (f) using said weighted averages for said first, second, third, . . . , Nth green cells to form a Gr-Gb balanced Bayer pattern.

17. A digital camera, comprising: (i) a sensor with Bayer pattern output; (ii) an image pipeline coupled to said sensor; and (iii) a Bayer pattern Gr-Gb balancer coupled to said image pipeline, said Bayer pattern Gr-Gb balancer operable to: (a) for a first green cell of a Bayer pattern array of cell amplitudes with first, second, third, . . . , Nth green cells where N is a positive integer, compute a closeness measure for each of the four adjacent green cells of the same Gr-Gb type as said first green cell; (b) for said first green cell using said closeness measures, compute weights for each of four adjacent green cells of the opposite Gr-Gb type as said first green cell; (c) for said first green cell using said weights, compute a weighted average with said four adjacent green cells of the opposite Gr-Gb type as said first green cell; (d) for each of said second, third, . . . , Nth green cells, repeat said steps of compute a closeness measure, compute weights, and compute a weighted average; and (e) using said weighted averages for said first, second, third, . . . , Nth green cells, form a Gr-Gb balanced Bayer pattern.